It is desirable to be able to completely power down a device when it is not in use or when it is disabled. For example, a laptop computer may have a wired LAN adapter and a wireless LAN adapter installed. When the laptop computer is moved from one location to another, the wireless LAN adapter may be used, for example, when no wired connection is available, and the wired LAN adapter may not be needed. Accordingly, the wired LAN adapter may be disabled to save battery power on the laptop computer.
However, some chips may have circuitry whose functionality may be required even while the remainder of the chip may be powered down. For example, portions of the wired LAN adapter may need to have power even when the rest of the chip is powered down. These portions may be the circuitry that detects network signals if a network cable is plugged in to the laptop. This may happen if the laptop computer is moved to a location where there may not be a wireless hot spot, and accordingly a cable is plugged in to the laptop computer to access a wired LAN.
Similarly, some interfaces, such as, for example, PCI express (PCIe) serializer/deserializer (SerDes) may communicate status and/or commands with each other over a communication link even when there is no data to be transferred. In this manner, the PCIe SerDes may ensure that the communication link is still active. If a PCIe SerDes, for example, on the wired LAN adapter, is powered down, the PCIe SerDes at the other end of the communication link may assert a system error that its communication link is out of service. Therefore, the usage of additional power while the communication link is active may need to be balanced against the need to keep unwanted system errors from occurring.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.